Lead pencil with pressurized lead driving means

ABSTRACT

A lead pencil including a pressurized lead driving means for positioning a piece of writing lead at the writing position and a means to securely hold a substantial length of the lead within the pencil to prevent vibration and breakage problems.

United States Patent [72] lnventors Tsan-Chang Kuo No.6 115i Mia Li, Tu-kuh, Yung Lin llsien; Shan-Mu Hong. No. 259-10, C heng I North Road San Chung, Taipei Hsien, both of, Taiwan [21] Appl. No. 732,688 [22] Filed May 28, 1968 [45] Patented June 1, 1971 [54] LEAD PENCIL WITH PRESSURIZED LEAD DRIVING MEANS 8 Claims, 7 Drawing Figs.

[52] US. Cl 401/73, 401/172 [511 1nt.Cl B43k21/02 [50] Field ofSearch 401/57,58, 55,56, 75, 78, 73, 96

[56] References Cited UNITED STATES PATENTS 1,586,521 1/1926 Deli 401/73 2,638,074 5/1953 Hasselquist 401/73 2,902,754 9/1959 Lorenian 40l/79X 2,988,784 6/1961 Lorenian 401/96X 3,179,086 4/1965 Owandano 401/73X 1,891,324 12/1932 Ferguson 401/173 2,531,078 11/1950 Nilsen 401/173 2,072,922 3/1937 Norlin 401/57 2,207,810 7/1940 Link 401/57 1 FOREIGN PATENTS 22,321 12/1893 Great Britain 401/57 77,233 10/1893 Germany 401/57 Primary Examiner-Lawrence Charles Att0rney-Lane, Aitken, Dunner & Ziems ABSTRACT: A lead pencil including a pressurized lead driving means for positioning a piece of writing lead at the writing position and a means to securely hold a substantial length of the lead within the pencil to prevent vibration and breakage problems.

LEAD PENCIL WITH PRESSURIZED LEAD DRIVING Y MEANS BACKGROUND OF THE INVENTION In conventional lead pencils, the writing lead is driven by a screw-stem mechanism, which is turned by a control button or other portion of the pencil such as the cap, barrel and so forth. The turning of the screw forces ahead or retracts the drive stem within the barrel. This screw-stem construction is relatively expensive-and causes the cost of the pencil to be relatively high which limits its popularity.

Another disadvantage of conventional-type lead-filling pencils is that the lead is held only at one end by a metal socket attached to the drive stem while its dangling end is supported only at the point of the cap tip. This arrangement causes the lead to shake and vibrate during writing with the result that the lead often breaks.

Still another disadvantage of many conventional-type leadfilling pencils is that the lead is thick and sharpening becomes necessary for clear writing. Many models of lead pencils require a sharpening device as standard equipment.

SUMMARY OF THE INVENTION The present invention relates to pencils and more particularly, to lead pencils which are adapted to overcome the disadvantages of the prior art devices. The lead pencils of the present invention provide an improved driving mechanism wherein a lead driving medium of pressurized fluid or solid is applied against the writing lead. The pencil could be a singleuse type which is-discarded once the premounted lead is used up or it may be of the refillable type where the spare leads are stored within the empty space of the barrel.

The invention also contemplates using a means to securely hold a substantial length of lead within a lead holding socket to eliminate the vibration and breakage problems. With the pressure drive medium and the lead holding means described above, the writing lead may be of an extra fine size, so that sharpening will no longer be necessary to obtain sharp clear writing.

Among the objects of the present invention are the provisions of a lead pencil wherein the driving of lead is accomplished by a pressurized medium, the provision of a lead pencil having a means for securely holding substantially the entire length of the lead within the pencil and the provision of a lead pencil adapted to use extra fine writing lead eliminating the need for sharpening.

Other objects and further applicability of the present invention will become more apparent when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal view in section of a preferred embodiment of the'present invention;

FIG. la is a sectional view taken along the.line -111 of FIG. 1;

FIG. 2 is a longitudinal view in section of a second preferred embodiment of the present invention;

FIG. 3 is a cut away longitudinal view in section of a third embodiment of thepresent invention;

FIG. 3a is a sectional view taken along the line 3a3a of FIG. 3;

FIG. 4 is a cut away longitudinal view in section of a fourth embodiment of the present invention; and

FIG. 4a is a sectional view taken along the line 4a-4a of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lead pencil of the present invention includes a novel lead driving means wherein the writing lead is driven by a pressurized medium such as a fluid or solid material. The pressure force is transmitted through a movable drive means which acts like a piston or plunger in conjunction with a driving medium chamber. This arrangement is more economical than present screw-stem constructions; therefore, the design of the present invention should increase the popularity of lead pencils.

As illustrated in FIGS. 1 and la, the improved lead pencil includes an outer barrel 2, an inner barrel 3, a hydraulic pressure unit 4 and a metal lead holding socket 5. The socket 5 is provided with a longitudinal slot 51 which provides a degree of spring tension so that a constant holding pressure is provided against a substantial length of the end of the writing lead 6. The outer barrel 2 has a conically tapered section 21 at the tip into which three precast fins 22 are placed to support the front end of the inner barrel3. A seat 23 formed in the forward interior of the outer barrel 2 retains the retaining shoulder 52 of the lead holding socket 5. The rearward end of the interior bore of the outer barrel 2 is provided with threads to engage the threaded forward section of the pressure unit 4.

The inner barrel 3 rests its forward end against the retaining flange 52 of the lead holding socket 5. The rearward end of the inner barrel 3 is adapted to be inserted into the front end opening of the pressure unit 4. A fluidtight seal is provided at this point by a tightly fit packing ring 43 made of neoprene or plastic material and a retaining ring 44.

The pressure unit 4 comprises a hydraulic fluid chamber 41 into which a fluid suitable to be pressurized is filled to serve as a pressure medium. Such a fluid may be heavy cream (sodium stearate), brake fluid or the like. The chamber 41 opens at its foremost end into the bore of the inner barrel 3. A plug or piston 42 made of plastic or neoprene and having a diameter coincident to the diameter of the bore of the inner barrel 3 is placed within the inner barrel bore between the lead 6 and the fluid chamber 41. The plug 42 thus acts as both a seal and driving means. The pressure unit 4 is rotatably mounted within the outer barrel 2 so that by turning it clockwise, the fluid in the chamber 41 is pressurized and forced out of the chamber opening. The rearward opening 31 of the bore of the inner barrel 3 is bell shaped to facilitate flow of fluid into the bore of the inner barrel 3. This forces the plug 42 ahead within the bore of the inner barrel 3 which in turn pushes the piece of writing lead 6 to the writing position. With this arrangement a thin piece of writing lead may be used for sharp, clear writing.

The volume of the chamber 41 is so designed that when the pressure unit 4 is in its foremost position, the fluid is sufficient to just fill up the full length of the bore of the inner barrel 3 so that the writing lead 6 is driven out to its last trace. When this occurs, the driving plug 42 is positioned in the metal socket 5 to prevent fluid from flowing into the socket 5. Holes 32 are provided at the foremost end of the inner barrel 3 to allow the fluid to escape into the interior of the outer barrel 2 and to prevent fluid from leaking past the socket 5 and staining the paper. Once the fluid escapes through the holes 32, the driving force of the plug 42 is stopped and the pencil may be discarded.

A breather hole 45 is provided in the pressure unit 4 near the packing retaining ring 44 to let out air which may hamper the smooth insertion of lead into the bore of the inner barrel 3.

FIG. 2 illustrates a second embodiment of the invention wherein the pencil is refillable. Except for the following features, the structure and operation of the pencil la is the same as the pencil l illustrated in FIG. 1. The pencil 1a includes a separatable cap 7 in which three fins 22 are precast to support the inner barrel. Since the pencil la is refillable, the fluid outlet holes 32 are omitted. The empty space 8 between the inner barrel 3 and the outer barrel 2 is used for storing spare leads. These pieces of lead may be removed by unscrewing the cap 7, and thus the pencil Ia becomes refillable. The front cap 7 should be of transparent material to enable the visual inspection of the length of lead remaining in the pencil. Thus the pencil may be refilled before. the lead 6 in the pencil la runs out. This will prevent the plug 42 from being overdriven causing loss of the fluid through the socket 5.

A screwed on packing retainer 440 is used in place of the retainer ring 44 of the disposable pencil I. The retainer 44ais threaded into the lower bore opening of the fluid chamber 41. The screwed on packing retainer 44a assures a better fluid seal at this point since the fluid pressure unit 4 is designed for an indeterminate number of uses.

In the two embodiments described above, the lead 6 is driven forward by turning the pressure unit 4 clockwise. When the lead 6 is retracted, the pressure unit 4 is turned counterclockwise to enlarge the chamber 41 and the lead 6 is pushed back into the pencil by depressing the point on any solid surface. In the case of the refillable embodiment shown in FIG. 2, during the refilling operation, the pressure unit is retreated to its rearmost position and the lead is inserted into the socket 5 at the writing tip. The residual stub of the prior piece of lead may be left within the inner barrel of the pencil without alter ing its operation.

Within the scope of this invention, the lead may be driven by any pressurized medium. As illustrated in FIG. 3, a third embodiment of the pencil 1b uses solid material in place of fluid as the driving medium. A pressure unit 140 includes a chamber 141 which is provided with a tapered bottom 144. The chamber 141 contains a plurality of spherical solid particles 147, the diameter of which is preferably the same as the cross-sectional diameter of the writing lead 6. A channel 146 is formed on the tapered bottom 144 allowing the passage of a single solid particle 147. A driving stem 149 having the same diameter as the lead 6 is actuated by a turning screw 148 which is rotatably mounted at the rearward end of the pressure unit 140. The turning of the screw 148 is restricted so that the stem 149 is moved forward or retracted so as to allow one of the spherical particles 147 to pass from the chamber 141 through the channel 146.

While using the pencil lb of the third embodiment, the pen cil lb is held with its writing tip down. The screw 148 is retreated to allow one particle 147 to enter into the rear end of the inner barrel 3. The stem 149 is then driven forward to push the lead 6 by means of the solid particles 147 to the writing position. After the pencil is used, the screw 148 is retracted and the writing lead tip is pushed back into the inner barrel by pushing on a solid object.

The pressure unit 140 is preferably made of transparent material to facilitate visual inspection of the particle passing channel 146. If the particle in the channel 146 becomes stuck, the pencil is shaken slightly to release the particle 147.

FIG. 4 illustrates a fourth embodiment of the pencil 1c using another type of solid material driving medium. A pressure unit 204 is force fitted over a wooden barrel 202 and comprises a chamber 241 within which are stored cylindrical rods 247 which are used as the lead driving medium. The rods 247 are preferably the same diameter as the piece of lead 206 which is slidably fit within the bore of the wooden barrel 202. The front end of the pencil 1c is provided with a metal cap 253 having a projecting socket portion 254 to support the lead 206 in its writing position. A metallic snapring 255 is included inside of the tip of the cap 253 to insure that a substantial length of the lead 206 is securely held at the writing position. The pressure unit 204 further comprises a metallic driving stem 249 which is molded into a threaded plastic button 248 which is rotatably mounted within threaded opening 245 formed in the end of the pressure unit 204.

As illustrated in FIG. 4a, the chamber 241 includes a hook 246 formed integrally with the chamber wall and projecting into the center of the chamber 241. The center of the hook 246 is aligned with the bore of the barrel 202 and the driving stem 249, and is adapted to receive and position a single cylindrical rod 2470. With the rod 247a in this position, it may be slidably moved into the bore of the barrel 202 when the driving stem 249 is rotated inwardly to move the lead 206 to the writing position. After one of the rods 247 has been pushed by the driving stern 249 all the way into the bore of the barrel 2, the button 248 is rotated outwardly to retract the driving stem 249 from within the chamber 241. The pencil 1c is then rotated and another cylindrical rod 247 is dropped into the center of the hook 246 so as to be aligned with the lead 206.

The button 248 is again rotated inwardly to push the lead 206 further through the barrel 202.

The total number of rods 247 which are stored within the chamber 241 have a linear length equal to the length of the bore of the barrel 202 so that the lead 206 may be used to its last trace.

The pressure unit 204 is preferably made of a transparent plastic material so that a visual inspection may be made of the position of the driving rods 247 to be sure the rods 247 are properly aligned in the hook 246 before the driving stem 249 is actuated.

It will be appreciated that the above description of the embodiments are illustrative only and numerous modifications and variations may be made in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

We claim:

1. A lead pencil comprising:

a housing including a first portion and a second portion together defining a cavity within said body, said first portion being threaded along a length of its interior, said second portion defining an opening communicating with said cavity and the exterior of said housing through which a piece of writing lead is capable of being projected into a writing position,

means within said housing for supporting said piece of writing lead along a length near one end thereof and in a posi' tion aligned with said opening,

an inner member secured within said cavity in said housing and defining a bore for receiving a length of said piece of lead, said bore being in alignment with said opening in said housing, a threaded element rotatably secured to said first portion of said housing and defining a chamber,

a force-transferring medium located in said chamber for translating the rotational movement of said element relative to said first portion of said housing into a force which is applied to said piece of writing lead when the effective volume of said cavity in said element is thus reduced, and,

means for transferring said force from said force-transferring medium to said piece of writing lead while in said aligned position through said opening to said writing position transferring means being located between said piece of writing lead and said force-transferring medium and cooperating with said bore to prevent the passage of said force-transferring medium past said transferring means into said bore as said element is rotated relative to said first portion of said housing to advance said piece of writing lead and cooperating with said supporting means to prevent a flow of force-transferring medium into said supporting means when said piece of writing lead has been substantially completely projected from said bore.

2. The lead pencil as defined in claim 1 wherein said supporting means is a lead'holding socket member secured in said opening and defining a slot longitudinally located therein.

3. A lead pencil as defined in claim 2 wherein said forcetransferring medium comprises a fluid, and said inner member includes means to vent said fluid from said chamber and said bore when said transferring means has moved to its foremost position adjacent said socket member to prevent leakage of said fluid from the pencil.

4. The lead pencil as defined in claim 1 wherein said forcetransferring means includes a plug member slidably secured in said bore and forming a fluidtight seal therewith, one end of said plug member being in contact with said piece of lead, the other end of said plug member being in contact with said force-transferring medium.

5. The lead pencil as defined in claim 4 wherein the bore in said inner member is inwardly tapered at the end thereof in contact with said force-transferring medium.

6. The lead pencil as defined in claim 4 further including means for providing a fluidtight seal between said housing, said inner member, and said element.

8. The lead pencil as defined in claim 1 wherein said second portion is separable from said first position of said housing so that extra pieces of lead may be stored in the opening between i said inner member and said housing. 

1. A lead pencil comprising: a housing including a first portion and a second portion together defining a cavity within said body, said first portion being threaded along a length of its interior, said second portion defining an opening communicating with said cavity and the exterior of said housing through which a piece of writing lead is capable of being projected into a writing position, means within said housing for supporting said piece of writing lead along a length near one end thereof and in a position aligned with said opening, an inner member secured within said cavity in said housing and defining a bore for receiving a length of said piece of lead, said bore being in alignment with said opening in said housing, a threaded element rotatably secured to said first portion of said housing and defining a chamber, a force-transferring medium located in said chamber for translating the rotational movement of said element relative to said first portion of said housing into a force which is applied to said piece of writing lead when the effective volume of said cavity in said element is thus reduced, and, means for transferring said force from said force-transferring medium to said piece of writing lead while in said aligned position through said opening to said writing position transferring means being located between said piece of writing lead and said force-transferring medium and cooperating with said bore to prevent the passage of said force-transferring medium past said transferring means into Said bore as said element is rotated relative to said first portion of said housing to advance said piece of writing lead and cooperating with said supporting means to prevent a flow of forcetransferring medium into said supporting means when said piece of writing lead has been substantially completely projected from said bore.
 2. The lead pencil as defined in claim 1 wherein said supporting means is a lead-holding socket member secured in said opening and defining a slot longitudinally located therein.
 3. A lead pencil as defined in claim 2 wherein said force-transferring medium comprises a fluid, and said inner member includes means to vent said fluid from said chamber and said bore when said transferring means has moved to its foremost position adjacent said socket member to prevent leakage of said fluid from the pencil.
 4. The lead pencil as defined in claim 1 wherein said force-transferring means includes a plug member slidably secured in said bore and forming a fluidtight seal therewith, one end of said plug member being in contact with said piece of lead, the other end of said plug member being in contact with said force-transferring medium.
 5. The lead pencil as defined in claim 4 wherein the bore in said inner member is inwardly tapered at the end thereof in contact with said force-transferring medium.
 6. The lead pencil as defined in claim 4 further including means for providing a fluidtight seal between said housing, said inner member, and said element.
 7. The lead pencil as defined in claim 6 wherein said element defines a recess and said sealing means comprises a packing ring disposed about said inner member and located in said recess in said element, and a retaining ring disposed about said inner member adjacent said packing ring and also located in said recess in said element.
 8. The lead pencil as defined in claim 1 wherein said second portion is separable from said first position of said housing so that extra pieces of lead may be stored in the opening between said inner member and said housing. 